coast219

could you give details and pics on the RC diving bell with a sealed ballast tank you mentioned a while back.

petn7

the diving bell was bascially a large plastic container (like the ones you get from the supermarket that has like 8 cups of yogurt or sour cream.) inside that plastic container was lead ballast weights, 2 plastic bottles, and a motor driven pump. those plastic bottles were almost indentical to the ones i used in the Alfa sub WTC. one bottle was the WTC. it had the receiver, ESC, and main battery. only 2 wires came out of the WTC - the motor wires from the ESC (which was reversible btw.) those 2 wires connected to a motor that ran the pump; the motor ran wet in the water (didn't last too long either). from this pump i connected a tube which went to the other plastic bottle. this plastic bottle had a hole cut in the top of the where the plastic tube from the pump went. this was glued with silicon glue. where the tube came out of the other end, i attached a balloon and rubber-banded it to the plastic tube. i screwed the cap on the bottle so that the balloon was sealed inside the plastic bottle.

when trimmed out, i sent the signal to the receiver to power the pump. the pump then filled the sealed ballast tank by putting water in the balloon - making the diving bell sink. of course, since it was a sealed pressure ballast tank, i had the keep the pump running to keep the water from coming back out ( i had no valve either.) to surface i reversed the pump to empty the ballast tank. it was a rather simple design that could go to at least 9.5 feet.

coast219

- thanks for the info. I might try incorporating that into my system.

petn7

I updated the Alfa with anhedral fins and a new WTC:

Taxidriver

Nice does it work?

petn7

Of course it works, but I have yet to test the submarine with the new anhedral fins. I hope that the rolling in the turns will be reduced.

CrunchyFrog

Petn, that is so very cool !

Keep a zero bubble

petn7

Thanks Crunchy

TomHanrath

Thank for posting so much of your own work. I recently got it into my head to build a sub...I eventually want it to be semi-independent but that is a long time in the future. One point that is going to be a real problem for me is:
"How does one have a water proof drive shaft/prop"?

Every time I converse with RC boaters...they mention that the interior doesn't stay dry.
I have a feeling that building a sub this is going to be a major problem and the solutions that RC boaters have may not be suitable for pressure or depth.

I've looked all over the net for "sealed bearings"...but I'm wondering what these RC model subs use? The bearings information I'm finding is for larger applications then I'm prepared to do. Does anyone know where I can get "sealed bearings" suitable to an RC Submarine...and maybe a little fancier for depth (future plans)?

Once I have these in my hands...I'll start figuring out where to get a prop and such...but can't do to much more without solving this problem.

Thanks!

Tom

petn7

Tom,

There are several sites you can check out for more forums:

www.subcommittee.com
www.rcgroups.com
www.subpirates.com (although they have their own, "culture" which might take getting used to)

As for prop shaft seals, they make special seals for our submarine use. You can get them from http://www.caswellplating.com/models/propeller.html or http://www.mikessubworks.com You can also get pushrod seals from those places as well.

TomHanrath

Thanks! I've got some reading to do.
I'm hoping to find something that will not cause too much battery drain...an will handle deep depths...even 30m or so. Perhaps I'm dreaming. <grin>

petn7

Battery drain shouldn't be a problem. Most subs get hours of run time on a single charge. Of course, my Alfa sub from this thread only gets slightly over 20 minutes of run time, but I'm only using 400mah NiMH cells. Most people use lead acid cells or SC cells used with R/C cars and gets hours and hours and hours of runtime.

Some also use lithium cells, but I only think they are necessary for small subs like mine. Even then, 20 minutes are enough and it's not work risking a fire in a WTC.

I doubt you can get 30 meters of depth with standard R/C equipment. In a clean lake, you probably can't get more than 8 meters of depth range. In a pool, be happy if you can get over 3 meters. But maybe you plan on using an umbilical, so no worries then.

TomHanrath

Yah...I was aware of the line of sight thing. That's what worries me a bit about finding what I need. I'm moving (slowly and having fun on the way) towards a "semi-independent" submersible which will use some of the concepts of "robotics" to be programable. I know its a bit far fetched...but I am working on creating something that can operate a little more independently...the first challenge among many to come is the mechanics of operating that deep.
And of course since RC doesn't typically do that...I think that may be my first hurdle. <grin>

Still, the basics of submersibles is already a lot to learn...and I'll be shallower depths and RC for quite some time I think...and loving the learning the whole time.

I appreciate the input I get from you as that kind of thing could keep me from stubbing my toe a lot.

thanks again,

Tom

petn7

No problem

Just take small steps, otherwise you risk getting discouraged when things don't go along swimmingly.

TomHanrath

Heheheheheh. Yes! And the small steps help disguise the overall costs with my wife. <grin>

CrunchyFrog

Holiday weekend's here ! I took out my two-months-decommissioned shoestring-budget homebuilt sub (dynamic diving; PVC watertight chamber inside a 1-144 scale SSN 21 Seawolf hull) and started checking it over.

Prop spun up silently...rudder snapped to attention both ways, no problem.

It was like my project had noticed my absence, and wanted to lull me back in promising none of her past tricks ! [sm=kiss.gif]

After my son's bedtime, I took the sub to his blowup pool for trimming. Prop ran for two seconds and quit. [sm=drowning.gif]

After a laugh at the sub, I realized the sub WAS responding but I'd forgotten a few things: The sub was lit, but I'd been sitting in the dark and didn't realize I'd had the tx stick in reverse (never the sub's optimal speed, so it wasn't moving fast). Plus the hastily-borrowed batteries I'd thought fresh were in reality shot.

I switched to Ahead, and saw the sub wake up and respond to rudder. I need to give my sub some credit. It wasn't trying to full a fast one, I just forgot things can be a little tricky when my family's in bed and I'm keeping lights low !

petn7

I finally got to run the Alfa V2 in open water, and realized some trim/balance changes need to be made. Because of the new battery pack, extra cell, and new motor, the torque produced by the propeller causes the Alfa V2 to CONTINUOUSLY roll under full throttle. We're not talking about the sub tilting over or even listing 90 degrees under throttle...we're talking a non stop rolling of the sub under full throttle like the Alfa V2 is a rifle bullet. Looks like I'll have to add some weight to the sub as well as foam. The Alfa V2 will not have the acceleration and stopping speed I had hoped, but I guess I have no choice.

CrunchyFrog

Good luck...maybe it won't really take that much weight to stop the roll?

petn7

I don't know how much weight I'll need. I'll just do some experimenting. After all, this wouldn't be such a great hobby if we always got it right the first try. [8D]

CrunchyFrog

Heh no kidding !

I just put navigation lights on the conning tower. Version 2.0 for those, because on my first try I made the little two-LED package too big and couldn't close the sail halves around it. [:@]

petn7

Ok, I managed to find a pool to have a rest run. The rolling has been fixed, but there's a serious leak. Due to the fact that the Alfa V2 sits so low in the water, any leak can be very serious considering this is a dynamic diver. I'm guessing the leak is in one of the pushrod seals. Maybe a little silicone grease will help. More "bathtub testing" is needed.

Other than the leak, she handled great.

CrunchyFrog

Congrats Petn ! Man that's exciting. Must be a big relief that it doesn't roll now. I'll bet it's gonna be lots of fun to drive the new and improved Alfa.

Good luck finding the leak. I stayed in drydock for months because of a leak (and a related slump in interest) this year. I kept suspecting my prop shaft seal...but whenever I tested the WTC end cap, there was not enough water coming in to account for the leak. Felt really dumb when I realized I had not checked the WTC breakdown point where I detach the end cap from the pipe. It was the culprit, the gasket had worn down gradually enough I hadn't noticed it happening. Maybe it sounds as though it should have been horribly conspicuousbut I have about a dozen WTC penetrations including propshaft, and had suspected one of them instead.

I've been prepping some new sub electronics. Last night I pulled a circuit board from a two-channel toy r/c car for transplant...easy cut 'n' snip operation...tested by relinking via quick connectors with an independent power source and the car's own motors...board worked just like it had never been extracted from the body. Then I took it out tonight to link it with the functions it was going to run...no joy at all ! Baffling...batteries fresh...meter practically jumps up and down to say there are no bad connections when I test...power gets to the board...could the IC have croaked just sitting on the shelf ? Reconnecting to the car body to try to figure it out, I notice the car acts narcoleptic: for 10 or 15 minutes or more it won't respond at all to anything...then wakes up briefly, a few responses consecutively IF the tx is close to the car...then dormant again for a long time. I don't have a clue what changed between last night's 100% successful test and now.

Blow negative to the mark !

CrunchyFrog

>could the IC have croaked just sitting on the shelf ?

I figured out what had been different between the two test sessions. In the second session, I brought out a second transmitter because the first tx wasn't working. Both gave no results, so I'd thought somehow the board had died.

But the battery in the first transmitter had been used after the first test, and I'd assumed it was still at a decent output the second night. Not so.
The battery was fine in the second tx. But it's an old tx and I've had it apart before, and as I sat down to a third test session, I noticed the coil was missing.

Duhhh. Two barely-signalling transmitters. Not a dead rx board. Whew.

petn7

After some diagnostic testing, I found where the leak was coming from: a damaged 1/16" pushrod seal. Looks like I'll drill it out and put a new one in. I'm guessing some JB Weld got into pushrod seal when I was gluing it into place. The seal did feel loose, so maybe the JB Weld damaged the o-ring somehow.

petn7

Ok, new pushrod seal installed. Now to wait for the JB Weld to dry...